We plan to do a nested case-control study using the MRFIT participants in order to determine whether; (1) serum insulin is a risk factor for CHD morbidity and mortality; (2) whether DHEAS is a risk factor for CHD mortality; and (3) the determinants of serum insulin levels among middle-aged men. The study will include 100 CHD deaths, 100 MI's, and 400 controls matched for age, and whether usual or special care participants in the MRFIT trial. Specimens have been stored at -60- -70C for about 15 years. Deaths have been ascertained in the MRFIT study since 1974. Surviving MI participants were carefully, evaluated during the active phase of the trial through 1982. Adequate numbers of cases are available based on recent reviews by the Coordinating Center. The possible relationship between either insulin or DHEAS and CHD mortality will be evaluated in relation to other major CHD risk factors including total cholesterol, LDL, HDL, triglycerides, fasting 1-hour blood sugar, systolic and diastolic blood pressure, BMI, physical activity, education, pulmonary function, cigarette smoking, and thiocynate levels.